1. Field of the Invention
The present disclosure relates to a developing device, a process cartridge, and an image forming device, the developing device and the process cartridge being used for an image forming device such as a copy machine, a printer, and a facsimile device that uses an electrophotographic system or an electrostatic recording system.
2. Description of the Related Art
Conventionally, in an image forming device using, for example, an electrophotographic system, a developing device that develops using a developer an electrostatic latent image formed on an electrophotographic photosensitive member (photosensitive member) that is an image bearing member is used. The developing device bears a developer on a developer bearing member and conveys the developer. A developer regulating member regulates and charges the developer on the developer bearing member so as to supply the developer to the electrostatic latent image on the photosensitive member opposite to the developer bearing member.
To regulate and charge the developer on the developer bearing member, a method for bringing an elastic member generally formed in a blade shape as a developer regulating member into contact with the developer bearing member is widely used.
Japanese Patent Application Laid-Open No. 2003-195628 discusses a structure in which a shape of a tip portion on a free end side of a developer regulating member in each end portion in a longitudinal direction of the developer regulating member differs from that in a center portion in the longitudinal direction of the developer regulating member so that an amount of developer at each end portion in a longitudinal direction of the developer bearing member differs from that at a center portion in the longitudinal direction of the developer bearing member.
Generally, a roller-shaped (or sleeve shape) developer bearing member is disposed such that a part in a circumferential direction of the developer bearing member is exposed from an opening portion of a container that contains the developer of the developing device. Thus, the developing device has end sealing members that are brought into contact with the part in the circumferential direction of the developer bearing member so as to prevent toner from leaking from the end portions in the longitudinal direction of the developer bearing member. When the developer regulating member comes into contact with the developer bearing member, it is effective to surround the end portions in the longitudinal direction of the developer regulating member with the end sealing members and the developer bearing member so as to prevent toner from leaking from the end portions in the longitudinal direction of the developer regulating member.
However, the inventors of the present invention know that the degree of adhesion between the developer regulating member and the developer bearing member may degrade at a portion where the end sealing members and the developer regulating member overlap depending on a shape of the developer regulating member. In particular, as will be described in detail below, when image quality is secured, a sufficient space is formed for a developer circulated between a predetermined region on the free end side of the developer regulating member and the developer bearing member. In this situation, the inventors know that the degree of adhesion tends to degrade. When the degree of adhesion between the developer regulating member and the developer bearing member degrades, it is likely that the developer enters into a portion between the region of the developer regulating member and the developer bearing member. The developer is likely to leak from the end portions in the longitudinal direction of the developer bearing member.
Thus, the developer has to be prevented from leaking.